Make drunk mix it in a beer (9)
I believe the answer is:
inebriate
'make drunk' is the definition.
('inebriate' can be a synonym of 'make drunk')
'mix it in a beer' is the wordplay.
'mix' indicates anagramming the letters.
'it'+'in'+'a'+'beer'='itinabeer'
'itinabeer' anagrammed gives 'INEBRIATE'.
(Other definitions for inebriate that I've seen before include "Make drunk" , "boozer" , "Get drunk" , "Exhilarate" , "Drunkard" .)